THE GARDEN phlox blooms madly in late July and August as the daylilies begin fading away.

In tiny gardens in town I doubt you would want phlox, since they take as much space as peonies and have a somewhat weedy air to them even when well grown.

But in wide borders or, for that matter, in a solid bed, nothing is more festive in late summer, provided there is full sun, deep soil and plenty of water available.

Phloxes usually fail in half-shady places, but where tomatoes flourish, the phlox does very well.

Pink, white, crimson, scarlet and purple are the main colors. I do not, myself, despise the magenta phlox (which is what you often get if you let the garden hybirds go to seed and grow up) but most gardeners sneer at it. Refined people speak of screaming red or screaming yellow flowers, though equally garish.

This time of year you see phlox plants in cans at garden centers, and if these are planted now and watered well they will bloom freely this summer.

In case you wondered, the lavendar and purple varieties like 'Amethyst' and 'Russian Violet' are distinct shades of violet and are not magenta.

White phloxes are especially admired at night when they show up well. 'Miss Lingard' is an early sort that blooms off and on, about knee height, and vastly admired. It is not so big and bouncy as the later kinds, like 'Mount Fujiyama' or 'White Admiral.'

Pinks tend toward salmon - yellow in the pink - like 'Sir John Falstaff' or toward rose - blue in the pink - like 'Charles Durant' and 'B. Symons-Jeune.' One of the handsomest of all phloxes is 'Dodo Hanbury Forbes,' which is a pink with a trifle of blue in it and passes for clear pink. It consorts better with the rose pinks than the salmons, however.

The standard red phlox nowadays is 'Starfire,' which is scarlet, but there are also rose-reds like 'Windsor.'

Two common nuisances with phlox are red spider mites and mildew. I prefer to ignore both (as who does not) and often they are no problem, especially if the phlox are given good sunny open positions and rich soil to begin with. More distressing are the eelworms which make the plants so stunted they are not worth growing.

They are avoided by growing new plants from cuttings, instead of dividing the roots.

Greedy gardeners have trouble thinning their phloxes, but the best results (the flowers are larger and showier) come from pinching out all but five of the stems. Every third year the clumps should be divided, either after the bloom season ends or in spring when the new shoots are not more than three inches high. (Otherwise it is a nuisance to keep them watered enough to prevent wilting.)

Peonies that are not well-established (from roots planted only last October) usually do not bloom their first spring, or, if they do bloom, they produce flowers not up to snuff. This is nothing to be alarmed at. The following spring they will increase in stature.

A thing to be cautious about is fertilizing peonies. Rotted manure makes them grow all right, but few friends of the peony use it, since outbreaks of botrytis blight often follow. Quite apart from that, peonies should not have sudden rich shots in the arm.

If, however, a peony plant has a starved look to it in June, when it should be the very picture of robust luxuriance, then a light application - say a handful - of 5-10-5 fertilizer well watered in, a few inches out from the stems, will put things to rights. Dehydrated cow manure, applied equally discreetly and watered and gingerly scratched in, also does well in my experience.

You want the plants to be vigorous and heavy, but not soft and rank. If, for some reason, a peony clump must be moved, wait till late September; don't try it now.